"This method is obsolete, it has been replaced by System.Configuration!System.Configuration.ConfigurationManager.AppSettings"

I found this problem in MSDN and i used System.Configuration.ConfigurationManager. But the new error happen: ConfigurationManager is not in System.Configuration. What can i do? How can i fix this problem. Thanks!

seems strange indeed, but this blog entry has some pointers
source: http://weblogs.asp.net/scottcate/archive/2005/06/13/412248.aspx
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The Original System.Configuration.ConfigurationSettings class is found in the System.dll assembly. There is a new assembly with all the new ConfigurationManager classes as System.Configuration.dll. Before using the ConfigurationManager class, you must first set a reference to the new System.Configuration.dll.
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